1. Field of the Invention
The present invention relates to rendering devices and, more specifically, to a rendering device for processing images of around a vehicle captured by image capture devices, and generating an image for display on a display device.
2. Description of the Background Art
Exemplified for such rendering device is a monitor device disclosed in Japanese Patent Laid-Open Publication No. 11-338074 (99-338074). FIG. 35 is a block diagram showing the entire structure of the monitor device, including a first CCD camera 1001, a second CCD camera 1002, a control unit 1003, and a display unit 1004.
The first CCD camera 1001 is placed at the front-left corner of the vehicle, and captures an image of the front-left area ahead of the vehicle towards the heading direction thereof. Thus captured image is referred to as left-side image Scls. Similarly, the second CCD camera 1002 is placed at the front-right corner of the vehicle, and an image captured thereby is referred to as right-side image Scrs.
The control unit 1003 includes, roughly, an image generation device 1005, and an image overlay device 1006. The image generation device 1005 generates a trimming image Sctr and a vehicle image Scve. Here, as shown in FIG. 36, the trimming image Sctr is an image masked by a masking region Acmsk so that a left-side display region Acldp and a right-side display region Acrdp are formed on a display screen of the display device 1004. The vehicle image Scve represents the vehicle viewed from behind, and overlaid on the center of the trimming image Sctr as shown in FIG. 36.
Onto the resultant image having the vehicle image Scve overlaid on the trimming image Sctr, the image overlay device 1006 overlays the left-side image Scls and the right-side image Scrs captured by the first and second CCD cameras 1001 and 1002, respectively. Specifically, the left-side image Scls is overlaid onto the left-side display region Acldp, and the right-side image Scrs is overlaid onto the right-side display region Acrdp. The resultant image is a display image Scdp, which is displayed on the display device 1004. In the display image Scdp, the vehicle image Scve is located between the left- and right-side images Scls and Scrs, and thus the driver can appropriately recognize which image shows which side of the vehicle.
As such, the above monitor device carries two CCD cameras 1001 and 1002, but those cover only the front part of the vehicle. Recently, such CCD cameras have become commonly placed at right and left, and front and rear of the vehicle to capture images of thoroughly around the vehicle. If this is the case, the resultant image generated by simply overlaying the vehicle image Scve between the left- and right-side images Scls and Scrs may confuse the driver. That is, the driver cannot instantaneously recognize from which direction that the image he/she is seeing, covers. More specifically, assume a case that two CCD cameras are placed at the front side of the vehicle, and two more at the rear side thereof. The driver thus can see images covering both the front and rear sides of the vehicle, but cannot instantaneously tell which side of the vehicle he/she is now seeing through the image.